"We firmly believe that if Mr. Cohn departs the White House there will be a material market sell-off as he is running point on tax reform and considered as a front-runner to replace Federal Reserve Chair Yellen," Isaac Boltansky, an analyst at Compass Point, said in a note to clients.

Here's how Cohn, who bounced around from school to school as a young boy because "no one understood how to deal with a dyslexic kid," ended up as a key player on Wall Street and in the White House:

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Cohn's grandfather was a Polish immigrant who moved to the US on his own as a 13-year-old with $8 in his pocket. He worked three jobs, was an apprentice electrician, and ended up opening his own business. Cohn would later work there.

Cohn grew up in Cleveland in the 1960s in a middle-class family. He "bounced around from school to school because really no one understood how to deal with a dyslexic kid," he told colleague Jake Siewart in a podcast.

The Westinghouse Building on US Route 20 in Cleveland, near Edgewater Park, 1969.Wikimedia Commons

A teacher told Cohn's parents that "if they were really lucky and spent a lot of time' with Cohn, he might 'grow up to be a truck driver."

He ended up at Gilmour Academy, a Catholic school, where two brothers took an interest in his education. "I think they took an interest because I might have been the hardest-working kid in the class with the least amount of results," Cohn said.

He worked hard to get into college at American University, where he learned about time management. "You go to class less than 12 hours a week," he said. "If you can't figure out how to manage the rest of your time and get your work done, you should be questioning yourself."

Goldman Sachs recruited Cohn in 1990, marking the beginning of a 26-year career at the bank, where he dealt with different securities.

In 1994, he made partner. At the time, he was based in London, and managing a big trading book. "That first year as partner, you know, I got to the point where I was trying to be a trader and trying to be a manager and trying to manage the business," he said.

He decided to call his boss and spent 40 minutes on the phone telling him about how he wasn't able to balance trading and managing. His boss told him to figure it out and hung up on him.

Cohn realized he had to make a choice. "I came in the next morning, I called everyone in my department into a big conference room, and I announced to the room that I will no longer trade anything," he said.

Cohn quickly became a key figure in Trump's pro-business policies, often taking to TV to discuss the markets, tax reform and infrastructure spending.

Cohn was stood alongside Trump during the president's controversial press conference on Tuesday, where Trump said "both sides" were to blame for violence in Charlottesville over the weekend. Cohn was reportedly "upset" and "disgusted" with Trump's response.

President Trump is flanked by staff and cabinet members as he speaks about the Charlotte violence in New York
Thomson Reuters

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That led to speculation that Cohn might step down. Meanwhile, White House Chief Strategist Steve Bannon said in an interview that he battles with President Trump's economic advisers regularly. "We’re still fighting," he said. "There’s Treasury and Gary Cohn and Goldman Sachs lobbying.”

Steve Bannon.
Chip Somodevilla/Getty Images

Note: Prashanth Perumal contributed to an earlier version of this post.